Various types of industrial waste, such as chemical residues from chemical plants, wood dust containing substantial amount of formaldehyde and other poisonous raw chemical materials from mills for producing compound floors, fiber plate, synthetic plate etc., and medical waste from medical facilities, if not treated duly, would require space for storing them, and at the same time would cause very serious environmental pollution. Conventional processes for treating waste mainly comprises incineration and landfill. Since some poisonous chemicals contained in waste have a high burning point, however, they usually fail to decompose during the incineration process owing to incomplete combustion and thus remain in ashes or dusts. As a result, they cause environmental pollution and pose a serious threat to human health.
Moreover, most industrial waste often contain catalysts, including metals, metal oxides, or metal chlorides. When such waste is incinerated to decompose the poisons, the metals, metal oxides, or metal chlorides contained therein generally react with organics. Thus, the flue gas from the incineration process will contain poisons, including dusts, dioxins, and the like. These poisons flow with the flue gas and diffuse into the atmosphere. They invade the human body through skin, respiratory and tracts, and are carried into the human body by agriculture crops, thus posing a serious threat to human health.
In addition, dioxins are formed above 200° C. and degraded completely at 800° C.; however, it is re-formed at 200-400° C. Thus, when waste, such as chemical residues, medical waste, wood dust containing poisonous chemicals, etc. are incinerated, they must be incinerated in an incineration furnace to a full extent: they are subjected to a high-temperature incineration at a temperature of 1100-1300° C., so as to achieve a complete decomposition of the poisonous chemicals, in particular, dioxins contained in the waste. In order to avoid re-formation of dioxins at 200-400° C. in the high-temperature flue gas, the latter, at above 600° C., must be quenched to below 200° C. within one second so as to prevent re-forming of dioxins, and it must be cleaned for safe exhausting, as prescribed by some regulations concerning environmental protections.
With the increasingly stricter requirements of environmental protection regulations worldwide, extensive research has been carried out on processes and apparatus for treating waste, such as chemical residues, medical waste, wood dust and the like. For example, a device comprising a furnace for treating medical waste has been developed in Japan, wherein the medical waste is picked up by manipulators and then fed into the furnace hearth after the furnace door provided on the body is opened. Since the door must be opened when the waste is fed, the hearth temperature suffers a transient decrease, and thus cannot achieve the combustion temperature required by environmental protection regulations in a short period, which negatively affects incineration performance. Furthermore, since waste has various forms, such as liquid, particles, solid, etc., various processes and devices are necessary, depending upon the forms of the waste to be treated. Large capital investments on the part of enterprises, therefore, are required in apparatus for treating waste in various forms.